Apple iPhone SE
iOS 15.0
1 Find "Keypad"
Press the phone icon.
Press Keypad.
2 Divert all calls
Key in **21*+447836121121# and press the call icon.
**21*+447836121121#
3 Divert missed calls
Key in **61*+447836121121*20# and press the call icon.
Key in the required number of seconds before the call is diverted, e.g. 20. The number needs to be divisible by 5.
**61*+447836121121*20#
4 Divert if unavailable
Key in **62*+447836121121# and press the call icon.
**62*+447836121121#
5 Divert if busy
Key in **67*+447836121121# and press the call icon.
**67*+447836121121#
6 End call
Press Dismiss.
7 Return to the home screen
Press the Home key to return to the home screen.